(a) Field of the Invention
This invention is in the field of suspension liners intended to be used with prosthetic devices.
(b) Related Technology
Prosthesis suspension liners formed from silicone elastomeric materials have been described in prior patents, such as, for example, U.S. Pat. No. 4,923,474 issued May 8, 1990 to Klasson and Kristinsson (an inventor named in this application); U.S. Pat. No. 5,507,834 granted Apr. 16, 1996 to Laghi; and U.S. Pat. No. 5,376,129 granted Dec. 27, 1994 to Falkner and Walsh. Elastomeric suspension liners are used to cushion a post-operative stump or residual limb with respect to a prosthesis that is installed over the residual limb and coupled to the sleeve by a locking element, for example as described in the Falkner and Walsh patent No. 5,376,129. The suspension of the prosthesis occurs due to the suction of the liner against the residual limb (giving rise to the term "suction socket" used for such liners).
It is highly desirable in such liners that they conform closely with the residual limb, accommodate all surface contours and sub-surface bone elements of the residual limb and provide a comfortable cushion between the residual limb and the hard socket of the prosthesis that is to be fitted over the residual limb.
Special silicone rubber or elastomer materials have been formulated as suitable substances for suspension liners. Such elastomer materials having suitable hardness (or softness), elongation, tensile and other properties (sterilizability, non-porous, easily cleanable, etc.) have been used successfully for suspension liners.
The liner member disclosed in the Kiasson and Kristinsson U.S. Pat. No. 4,923,474 includes an elasticity controlling matrix material at the distal end of the sleeve that does not impede elasticity of the elastomer radially within the normal range of radial distension of the liner in normal use, but renders the liner substantially inelastic axially during use to minimize the "pumping" effect that can occur with a fully resilient liner at the distal end of a residual limb that may not be fully healed or sealed as discussed in this patent.
However, it is highly desirable to increase the comfort of such sleeve liners to enhance their ability to conform to irregularities on the residual limb, to accommodate a wider variety of residual limbs with fewer sizes of liners; and to provide the amputee with a total feeling of comfort at the residual limb interface with the prosthesis, all while maintaining strength and durability of the liner.